Question

'The extent to which a solute is dissociated or associated can be expressed by Van 't Hoff factor'. Substantiate the statement.

Answer 1

• The ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass,known as Van't Hoft factor.
• So,we can say that the extent to which a solute is dissociated or associated can be expressed by Van't Hoft factor.
• This is represented by $i$:
• $i=\frac{observedno.ofsoluteparticles}{Theoreticalno.ofsoluteparticles}$
• If $i>1$,the molecule are said to be dissociated.
• If $i=1$,the molecule have neither associated nor dissociated.
• If $i<1$,the molecule are said to be associated.
  

Example: $A_x{B}_y\rightleftharpoons x{A}^{y+}y{B}^{x-}$

At $t=0C00$

At $t=t_{f}C(1-\alpha )xC\alpha yC\alpha$ ($\alpha$ is the degree of dissociation)

SO ,$i=\frac{C(1-\alpha )+xC\alpha +yC\alpha }{C}$

$\Rightarrow (1-\alpha )+x\alpha +y\alpha$

$i=1+(x+y-1)\alpha$ (Here (x+y) are the total particles produced by one molecule of solute)